The register allocator needs to adjust its live interval unions when that happens.

llvm-svn: 127774

llvm-svn: 127773

llvm-svn: 127771

This allows the allocator to free any resources used by the virtual register,
including physical register assignments.

llvm-svn: 127560

This will we used for keeping register allocator data structures up to date
while LiveRangeEdit is trimming live intervals.

llvm-svn: 127300

LiveRangeEdit::eliminateDeadDefs() will eventually be used by coalescing,
splitting, and spilling for dead code elimination. It can delete chains of dead
instructions as long as there are no dependency loops.

llvm-svn: 127287

llvm-svn: 127181

llvm-svn: 126002

All new virtual registers created for spilling or splitting point back to their original.

llvm-svn: 125980

llvm-svn: 118661

give them individual stack slots once the are actually spilled.

llvm-svn: 117945

llvm-svn: 116962

llvm-svn: 116951

All registers created during splitting or spilling are assigned to the same
stack slot as the parent register.

When splitting or rematting, we may not spill at all. In that case the stack
slot is still assigned, but it will be dead.

llvm-svn: 116546

splitting or spillling, and to help with rematerialization.

Use LiveRangeEdit in InlineSpiller and SplitKit. This will eventually make it
possible to share remat code between InlineSpiller and SplitKit.

llvm-svn: 116543